This invention relates in general to dipsticks and more particularly to dipsticks which are to be fitted into dipstick guiding conduits having a curved portion or portions.
There have been proposed various dipsticks for use in measuring the level of the liquid in a container where the level cannot be checked directly with the eyes. Of these dipsticks, some are designed to be fitted into dipstick guiding conduits, such as in the case of automotive engine and transmission applications. That is, a known dipstick for automotive engines or transmissions is made of a steel bar material or materials and adapted such that when used to check the level of an oil it is inserted into a dipstick guiding conduit by a predetermined stroke and then pulled out to read the level by checking how it is wetted with the oil.
Referring to FIGS. 1 to 3 of the accompanying drawing of this application, some typical conventional dipsticks which are designed to be fitted into dipstick guiding conduits will be described:
FIG. 1 shows a dipstick 10 having a main body 12 and a handle portion 14 which are integrally formed of a single length of metal bar, e.g., a "SWRM" which is a standard mild steel round wire according to Japanese Industrial Standard, with a relatively large diameter d, e.g., 4.0 mm. This type dipstick 10 is adapted for use in straight dipstick guiding conduits and has an advantage that its handle portion 14 is rigid or stiff enough not to be deformed largely during its insertion into or pulling out of the associated dipstick guiding conduit. Furthermore, it has an advantage that it is less costly to manufacture due to its simple structure. However, this type dipstick 10 cannot be used in curved dipstick guiding conduits.
FIG. 2 shows another dipstick 18 having a main body 20 and a handle portion 22 which are formed as individual parts. The handle portion 22 is formed of a steel round bar with a relatively large diameter, so that the handle portion 22 is stiff enough not to be deformed largely by the force applied thereto when the dipstick 18 is inserted into or pulled out of the associated dipstick guiding conduit. The main body 20 is formed of a thin steel flat bar or a thin strip of steel sheets, so that the main body 20 is resiliently flexible in one direction, i.e., in the direction substantially perpendicular to its broader surfaces. The main body 20 and the handle portion 22 are joined together by rivets 24. With this structure, the dipstick 18 is insertable into curved dipstick guiding conduits of the kind which axially extend in one plane, i.e., two-dimensionally, since the main body 20 can flex in a manner as shown by the chain lines in the drawing to follow the associated curved dipstick guiding conduit. This type dipstick 18, however, has a disadvantage that it is more costly to manufacture for it requires two individual parts which are separately formed of different bar materials and assembled together thereafter. Furthermore, this type dipstick 18 cannot be used in such kind of curved dipstick guiding conduits that axially extend in two planes, i.e., three-dimensionally.
FIG. 3 shows a further dipstick 26 which is substantially simillar to that of FIG. 2 except that its main body 28 is adapted to be flexible in two directions. That is, as observed from the drawing, the main body 28 is twisted at the middle thereof to have such twisted form that the corresponding side surfaces of the upper and lower halves thereof (the left and right halves as viewed in the drawing) are substantially normal to each other. With this structure, the dipstick 26 is insertable into curved dipstick guiding conduits of the kind which axially extend in two planes, i.e., three-dimensionally. However, since each half of the main body 28 is flexible only in one direction and the flexible direction of each half of the main body 28 is fixed with respect to the flexible direction of the other half, this type dipstick 26 is not easy to handle. Furthermore, this type of dipstick 26 is much more costly to manufacture since it requires an increased number of manufacturing processes.